1. Field of the Invention
The present invention relates to a coil unit which is composed of stacked print coils, a substrate unit in which the coil unit is mounted on a main circuit substrate and a power supply device which is constituted so as to include the substrate unit.
2. Related Background Art
The power supply device is constituted with a semiconductor which serves as a switching element, coils such as a transformer and an inductor in which a ferrite core is used, a main circuit substrate which is electrically and mechanically connected to these electronic components, a control substrate which controls the electronic components, and the like.
Of these electronic components, in a coil component obtained by winding a coil around the core, an increase in capacity requires the coil width to be thick so as to withstand a high current or large current. Further, in order to increase step-up or step-down ratio between primary and secondary side, it is necessary to increase the number of coil windings. Therefore, in an attempt to prepare a coil component large in capacity or step-up or step-down ratio, the coil component is made larger in size, which poses a problem. For coping with the above problem, a print coil stack which is obtained by stacking flat coils, each having an insulating substrate on which a conductor pattern is printed, is used to downsize the coil component (refer to Patent Literature 1, for example).